Rocket projectile



E. F. CHANDLER I ROCKET PROJECTILE origig' grfil d July 19, 1944 Patented Oct. 3, 1959 UNITED STATES PATENT OFFICE 1 2,524,591 1 Y ROCKET PROJECTILE Edward F. Chandler, Brooklyn, it.- Original application July 19, 1944, Serial N04 545,585. Divided and t 1945, Serial No. 607,613

2 Claims. (o1.1'o2, 49 I This invention relates to projectiles of the automotive or rocket type, as well as to improved methods of firing reaction or rocket-type projectiles.

One of the objects of the present invention is to provide an improved rocket projectile of simple, inexpensive design which may be fired from a closed-breech, smooth-bore gun with results which are comparable with those obtained with regular ammunition and rifled guns, so far as accuracy and range are concerned. Another object of the invention is to provide a rocket projectile which is self-contained, and which may be manufactured, shipped, stored and handled in the field like ordinary fixed ammunition.

A further object is to provide a projectile of the reaction type which may be fired substantially without danger to the operator of the gun. Yet another important object of the present invention is the provision of a method of firing rocket projectiles wherein the inertia of the projectile-is instantaneously overcome, and the projectile is started upon its course when the firing operation is initiated.

It is an object, also, to provide means whereby, upon firing, the projectile, while still within the aiming influence of the launching means, is subjected to a spinning action for the purpose of stabilizing its trajectory. It is a further object of the invention to continue the spinning of the projectile at a substantially constant or an accelerating rate to afiord gyro-stability to the projectile while in flight.

Other objects and advantages of the invention will be hereinafter pointed out, or will become apparent as the specification proceeds.

Rockets constructed in accordance with the present invention can be fired accurately, in rapid succession, from smooth-bore guns of light weight and inexpensive construction. The gun may be breech-loaded, and the breech may 'be closed during firing. This is made practical by certain principles upon which the design of the projectile is predicated and the method of utilizing the same in the operation of the device.

In the usual form of rocket device, after the rocket propellent charge has been ignited, there is a considerable time lag before the generation of gas at suflicient pressure and velocity to start the projectile upon its course has developed. During this period, the gases which are generated are permitted to blast rearwardly from the rocket nozzle and from the open breech of the launching means, at about substantially the pressure at which said gases are being generated. This his applicationjuly 28,

method isv inefficient anddangerous to the oper-;.

ator. Because of the fire hazard, the use of such. a weapon for other than open field serviceis greatly limited. Furthermore, the flame blast is easily spotted by an enemy, which necessitates the changing of position after each shot. A rock-s et of this type cannot be'successfully fired from a closed-breech-gun, because, during the time-lag.. period referred to, the generation of gas pressure withinthe gun is relatively sufiiciently slow so that the projectile will be driven from the gun at such low velocity as to be devoid of aim and be virtually certain to follow an erratic course. In the present invention this and other disadvantages heretofore encountered are met and overcome. g V Among otherimprovements, the present inven-I,., tion embraces methods of, and means for, start-l; ing the projectile, in a spinning condition, ime-i mediately upon its course at substantially the; instant the firing operation'lis initiated. Them projectile is fired from a smooth-bore gun, prefs erablywhile the breech is closed. Uponfiring s. the projectile, it is subjected to an ejecting ime. pulse of sufiicient force to drive the same from! the gun at a relatively high muzzle velocity. This impulse may besufiicient to afford a muzzlevelocity of the order of from to 300 ft.. per; second. By igniting the rocket propellent charge substantially simultaneously with the firing Opera: tion, however, it is only necessary that the initial impulse drive the projectile over a short distance in order to furnish the rocket propellent charge.. suflicient time to become fully active. By this, means it will be seen that the time lag previously, referred to has been absorbed while the rocket device is in fiight, under the impulsion of the initial ejecting or, launching action. Thus, the projectile is started upon its course by one means; and continued thereon by another means. The initial ejecting force comes either from a source of energy carried by the projectile, or from means independent of the projectile. This initial eject-i ing force directly or indirectly starts the operation of the rocket propellent means. ,The two. effects are preferably so timed and correlated.) that the drivingof the projectile is transferred from the impulse action to the rocket. action. without disturbing the aimed direction originally impressed thereon.- 7 e i It is important that the projectile, when freed;

. from the directing influence of the gun, should spin on its longitudinal axis at sufiicient velocity to insure directional stability. It is also impor.-

tant that this rotational velocity be continued or accelerated during the power flight of the proj ectile. The projectile may be started spinning previous to firing to insure the desired rotational velocity upon launching. For example, the projectile may be spun by suitable means while within the gun barrel, or the gun barrel containing the projectile may be spun. The spinning of the projectile may, on the other hand, be initiated at the instant of firing by so positioning the reaction jets of the projectile as to establish rotary actionwhile within the gun barrel. This method isdescribed in detail hereinafter.

If the projectile is to be fired froma rapidlymoving platform, such as from an aircraft, it is desirable that the gun barrel be relatively short in order that the aim of the projectile shouldnot be disturbed by the changing position of the gun subsequent to the moment of firing. application of rocket ordnance, there is an importantadvantage in ore-spinning theprojectile. The: spinning operation may, for example, be started as the plane enters the target area, and thus be ready for immediate release and. be stabilized at a rotational velocity practically unobtainable by other means. Where projectiles are fired. from more stable platforms, however, and

from guns having relatively long barrels, or from.

smaller caliber arms, a high degree of accuracy of: fire is obtainable with the ammunition embodying the features herein described and illustrated, wherein both the initial driving and r tatingaction is imparted by the self-contained propelling means.

In the projectiles embodying features of the present invention, two powder charges are=e1nployed. One of these charges may. serve toafford the initial impulse for driving. and. rotating the projectile upon firing. The other may serve to take over and continue said driving and retating during the power flight of the projectile. Theinitial impuls-ion charge is preferably a quickburning, gas-evolving powder, or n explosive adapted to suddenly provide the heat and'pressure required to start the projectile on its course.

Thedriving or propelling charge, which may bea typical propellent rocket charge, is preferably a slower-burning powder especially adapted to be gradually and uniformly consumed while generating. a. relatively steady volume of gas under pressure.

In one form of the invention, the gases evolved from both powder charges are delivered to a.

single set of nozzles. Both charges are confined within a combustion or pressure chamber with which said nozzles are in gas discharge communication. The firing of one charge, the impulsion charge, immediately energizes the nozzles to start driving and rotating the projectile, and at the same time sets in action the second charge, namely; the rocket propulsion charge. This charge quickly commences to generate gas to augment and accelerate said action, and to continue supplying gas under pressure to the nozzles until the second charge is finally consumed. The initial impulse may be delivered in the form of'a comparatively large volume, low-pressure gas discharge. Also, a relatively high-pressure discharge of a-comparatively small gas volume maybe employed. Furthermore, if desired, the relation-between the factors may otherwise be so modified as :to afford the pressure-velocity effect found best suited to the condition to be met.

It will be understood that where this initial impulse is depended upon for the purpose f start- In suching the projectile from the gun, and not for the purpose of driving the projectile over its course, a comparatively small powder charge is required. Except for overcoming the inertia of the pro jectile, it is moved readily in the smooth bore of the gun and presents a much different problem from that of a shell which must be driven through a rifiedgun barrelrwith sufficient energy to' carry it over its entire range;

The method of operating rocket gun of the character disclosed herein is important from the standpoint of safety, both to the operator of the gun and to the craft or vehicle upon which the gun may be mounted. The gun being of the closed-breech type, there is no rearward flame blast, and,. also, due to the impulse launching method; the projectile may be drivento safe distance beyond the gun muzzle before'the full jet action of the rocket has been established. A further important feature of the present invention resides in the adaptability of the projectile for use in automatic arms. Rockets heretofore have not proven satisfactory as ammunition for rapid firing and gas-actuated automatic guns. One of the main objections to such use was in their sluggish initial action, 1. er, time lag followingdetonation, andfouling of.- the mechanism of the.

gun from the propellent rocket discharge. A projectile constructed in accordance with the present invention is initially fast acting, develops sufiicient primary energy to actuate automatic gunlmechanisms, and the operating explosive gas discharge doesnot-seriouslyfoul the gun parts. described is particularly. Well suited to automatic gun operation; the over-all length generally is less than a comparable cartridge case and shell, and cartridge-ejecting means are eliminated, thereby simplifying-the construction of the operating pparatus.

The present application is a-division of my 00-- pending application Serial-No.- 545,585, filed July 19, 1944, nowi-PatenttNo. 2,500,117, andalso constitutes a continuation-in-part of my co-pending application Serial No. 416,442, filed October25, 1941, now'Patent No; 2,504,648. It also: contains certain improvements inthe projectileandrmeth- 0d of shell propulsion described therein; The present application further is a continuation-in-- part of my co-pending application Serial No. 430,978, filed February 14, 1942, now-Patent No. 2,391,865.

In the drawing:

Fig. 1 shoWsa' projectile, partly in'longitudinal section, embodying the present invention.

Fig. 2 is a rear-endelevation' of the projectile shown in Fig. 1.

Fig. 3-shows a projectile, partly in' longitudinal section, embodying a modification-ofthe invention.

Fig. 4 is a transverse'section taken on-line 4 -4:

charge which may: be: detonated by a suitable l fuse 4|. Theishell 40 is attached-in any. desired manner to the afterbody section 42 :having a combustion space 431 which-zis. closed at the rear by. the wall .Mlandiis preferablyprovided with The rocket projectile of the type herein a forward closure that is removable, as shown. In discharge communication with the combustion space 43 are the obliquely-set nozzles 39 carried by the rear wall 44. Secured to, or formed as a part of, said rear wall is the tubular member 46, in the rear face of which is fixed the percussion cap 41 which is adapted to detonate the powder charge 48 in the cavity 49. The forward opening of the cavity 49 is sealed by a thin diaphragm 58 which is adapted to restrain the explosive energy of the detonated powder charge 48 until the diaphragm is disrupted by a predetermined gas pressure, thus permitting the gas to escape into the combustion space 43 and to issue therefrom through the nozzles 39. In the forward end of space 43 is positioned the rocket propellent charge 53 which is adapted to be ignited by the percussion cap 5|. Percussion cap 5| is detonated by the firing pin 52 which is caused to strike said cap upon the explosion of the powder charge 48 upon the bursting of. the

diaphragm 50.

The action of the rocket propellent charge may be modified by associating therewith, or embedding therein, a special powder charge 54. This charge 54 may be a fast-burning, gas-evolving compound for the purpose of initially stepping up the pressure within the space 43. It may aid in the ignition of the main charge 53, or it may otherwise be used to regulate the action of the jets, as, for example, by governing the extent of the surface area exposed to combustion. In Fig. 2, the general appearance of the projectile, viewed from the rear end, is shown.

This design is well adapted for rocket ammunition of various calibers, and is especially suitable for use in small arms, automatic guns, and repeating weapons. Positioned in a closed-breech, smooth-bore gun, the projectile is fired by causing the firing pin of the gun to strike the percussion cap 41, whereupon the powder charge 48 is detonated and generates a sufiiciently high, predetermined pressure within the cavity 49 to burst the diaphragm 50. The gas discharge thus released enters the space 43, from which it issues through the nozzles 45 into the gun barrel behind the projectile. The rapidly-expanding gas drives the projectile from the gun barrel at high velocity and rotation, due to the angular thrust of the jets from the obliquely-positioned nozzles.

Ignition of the rocket charge 53 having been simultaneously initiated at the instant of firing, rapidly becomes active and takes over the driving and rotation of the projectile at substantially a predetermined distance beyond the gun muzzle. The power of the initial driving impulse may 'be adjusted and controlled by the weight and characteristics of the powder charge 48 employed, and by the resistance of the diaphragm to meet desired service conditions, and for the type of arm in which the projectile is to be used.

In Fig. 3, is the forward shell section, and may carry any desired kind of charge, and may be equipped with a suitable detonator 6|. This forward section 60 is secured to, or carried in any suitable manner by, a mid-section 62, into which is screwed, or otherwise secured, an afterbody section 63, which is provided with a combustion space 64 which is in discharge communication with suitably-formed, rearwardly-directed, oblique nozzle openings 65. Adjacent its forward end, afterbody 63 is provided with a plurality of openings 24 which communicate with the obliquely-disposed nozzle openings 65 which may be formed as follows. The blank used in forming afterbody 63 may have, adjacent its forwardend, an enlarged annular shoulder whose outer periphery is defined by line 25. A plurality of spaced, diagonally-disposed slots 65 may be milled,

into this shoulder, forming the nozzle openings which are defined at opposite sides thereof by the intermediate or land portions 21. The rear terminal of mid-section 62 .is provided with a longitudinal bore 23 of substantially the same diameter as, that of shoulder 25, and ac'cordingly, when the parts are assembled, as shown at Figs. 3 and 4, the walls of the nozzle openings are M formed. 7

Within the combustion space 64 is positioned a rocket propellent charge 66 having an axial bore, which may be tapered, as shown. Within this bore is a powder charge 67. Thischarge BT may be a quick-burning powder charge, and

serves to supply initial gas pressure for energizing the jets upon firing, and also to initiate combustion of the rocket'charge 56 by igniting the same within said bore; The chargesmay be ignited by a suitable primer "68 in the'buttof the projectile, and which is in direct communication with the powder charge 61. This projectile embrace's'in a simplified form someofthe featain applications of the inventive idea, to supplyto the nozzles a relatively large volume of relatively low-pressure gas rather than to afford the more rapid, explosive-like blast from the nozzles, which may be produced by confining the explo-;

sion until a predetermined, comparatively high.

pressure is obtained. In other respects, the principles of operation are substantially similar to that of the structure of Fig. 1. The cross-section on the line 44 in Fig. 3 shows the general form and arrangement of the reaction nozzles 65.

In Fig. 5, is the forward shell section which is adapted to carry any desired type of charge which may be detonated or activated, for exam- .ple, by'suitable means 8|. The forward section 88 is joined in any suitable manner to the hollow, afterbody section 82, having a closed end 33,.at the rear, and a removable closure member 84 at the forward end. Carriedv by the rear wall 83,

and projecting intothe space 85, is a tubular member 86 containing a powder chargef8'l.

Formed'in the rear wall 83 are a plurality of nozzles 88 which are obliquely positioned and in discharge communication with the space 85. In the center of the rear wall, and in communication with the powder charge 81, is a cap or other ignition means 89. A rocket propellent powder charge 90 is positionedwithin the space forward of the charge-carrying member 86, and is adapted to be ignited when the powder charge 87 is detonated. The insert 9!, in the rear face of the rocket charge 90, may be a special quick-burning powder to augment the initial gas evolution, or it may represent means for delaying or localizing combustion during a stage of the operation I of the system. A rear-end view of the projectile is shown in Fig. 6. 7

The projectile shown in Fig. 5 is a simplified design in which features of the inventive idea are embodied. Upon detonation of the charge 81 by awn-sar theiignition'means'fis, gas pressure and heat are tion of the rocket charge 90 is initiated and =begins: generating gas under pressure to continue driving androtating the projectile at an accelerating-velocity. Aside from its use as a weapon, a simplified rocket projectile of this type is well adapted for use in connection with the projection-intotheair of signal flares, parachute distress flares, and the like.

Manyof the so-called rockets presently in use are not true reaction-propelled projectiles in that,- to insure a sufilciently high launching velocity, it: is necessary to consume 80% or'rnore of'the rocket propellent charge while the projectileisin the launching means. Accordingly, while-the projectile then leaves the launcher at a relatively high initial velocity, this velocity decreases as the projectile approaches its target because the reaction eifect of a true rocket isabsent. Because of the time lag between the; ignition of the rocket propellent and the generation of sufficient energy to drive the projectile, it has been found necessary to fire such projectiles'at a relatively high angle of departure, theweight of the projectile retaining the same in position in the launcher. However, in the firing of rocket projectiles of the class described herein in which a relatively high initial velocity is attained; it is possible to greatly reduce the angleof departure, and, in some cases, as for example onaircraft, tofire-at angles below the horizontal, in which instance means must be provided to retain the projectile in, place, in the launching means or gun until the projectile is fired. For this purpose, detent means, as described in my co-pending application Serial No. 408,284, filed August 26, 1941, now Patent No. 2,391,864, may be employed. It has been found advantageous, however, to employ magnetic means for retaining the projectile in position within the launch ing means or gun. A permanent magnet associated with the gun may be caused to retain the projectile, the launching impulse overcoming theholdingforce of the magnet. Also, electro-magnetic means may be employed in which the holding force is interrupted at the instant of firing. suchlmeans are simple, rugged, and lend themselves well to cases wherein either the projectile, or the gun containing the projectile, is rotated for the purpose herein outlined.

While-three forms or embodiments of the invention have been shown and described herein for illustrative purposes, and the construction and arrangement incidental to three specific appli'cations thereof have been disclosed and discussed in detail, it is to be understood that the invention is limited neither 'tothe mere details or relative arrangementof parts, nor to itsspe cific embodiments' shown herein, but that ex-;

tensive deviations from the illustrated forms or embodiments of theinvention may be made withoutdeparting from the principles thereof.

What I claim A is: 1. A rocket projectile having an opening providing a plurality of axially-aligned, chargereceiving cavities, and a combustion chamber therebetween communicating with each of such cavities, the projectile further having a plurality of obliquely-set openings extending rearwardly fromthe combustion chamber and formingjetlike nozzles, a quick-burning powder charge in i one of" such cavities, a frangible closure plate:

normally separating such cavity from the com bastion chamber, adapted to be ruptured upon" quick-burning powder charge, propellent detonation of such meansi'for: detonating such' charge, a

rocket charge in another of such cavities, and means adapted to ignite the propellent" rocket chargesupon the fractureof the closure plate.

2. A rocket projectile formed with anopening'thereinforming a combustion chamoer, and a plurality of charge-receiving cavities in: axial alignment with each other disposed at opposite ends of the combustion chamber, the

afterbody'further having aplurality of obliquely- REFERENCES CITED The following references are of record in the file of 'this patent:

UNITED. STATES PATENTS Number Name Date 579,035? Bell Mar. 16, 189?- 1,504,144 Romberg Aug. 5, 1924 1,880,579 Tiling Oct. 4, 1932 1,994,490 Skinner Mar. 19, 1935 FOREIGN PATENTS Number Country Date 73,840 Germany Mar. 9-, 1894: 379,664 Italy Apr. 2, 1940' 503,166 France Mar. 10, 1920:

a forward section and an afterbody, the afterbody having 

